It is known to provide torsional vibration damping disks (or spring retainer plates) with spring elements located within the periphery of the retainer. Prior art spring retainer plates used one or more support segments radially inward of the spring elements to retain the spring elements within the retainer plate and prevent the spring elements from falling out.
U.S. Pat. No. 6,675,457 discloses a one-piece torsional vibration damper retainer plate in which the annular periphery of the retainer plate is curled. The retainer plate is then heat treated and spring elements are located within the heat treated annular periphery. The final step is to completely curl the annular periphery about the spring elements to form a generally C-shaped channel to substantially surround the spring elements to prevent the spring elements from being removed from the C-shaped channel of the retainer plate. Unfortunately, the spring elements cannot be removed after the final curling. Therefore, if there is a defect in any of the springs, the entire retainer plate must be scrapped, since the spring elements are not replaceable. Further, undesirable deformation in the curled portion can occur since a relatively large portion of the curled portion is manipulated in each step to reduce production costs and the curled portion of the retainer is not fully supported during the curling process.
Thus, there is a long-felt need for a method to form a torsional vibration damping disk from one piece which is capable of holding spring elements without additional components while still allowing removal of the spring elements and reducing deformation of the disk during production.